Prior art round balers generally have a bale forming chamber defined by an apron comprising an array of side-by-side belts, transverse slats trained on chains, a plurality of rolls or a combination of these various elements, e.g., rolls and belts. Crop material, such as hay, is picked up from the ground, as the baler travels across the field, and is fed into a fixed or expandable chamber where it is rolled up to form a compact cylindrical package of crop material. While still inside the bale forming chamber in its compacted form, the outer surface of the package is wrapped with twine or web material, such as net, prior to ejecting the wrapped bale from the chamber onto the ground for subsequent handling.
Exemplary of prior art round balers of the general type mentioned above is the baler disclosed in U.S. Pat. No. 4,956,968 issued in the name of K. R. Underhill on Sep. 18, 1990. In this baler an apron consisting of a combination of rolls and belts is used for bale formation. The baler also includes a mechanism for supplying net to a dispensing assembly which in turn feeds the net material into the bale forming chamber for circumferentially wrapping a formed cylindrical package of crop material.
The dispensing mechanism includes a net insertion arrangement having a grasping portion for pulling net from the supply mechanism and inserting the free edge, commonly referred to as the tail, into the chamber. It is important that this tail be of adequate length to assure initiation of the wrapping operation, i.e., when the tail is placed in the chamber it must be of sufficient length to reach the nip between the cylindrical crop package and the bale forming elements that rotate the package during wrapping. As the package is rotated the tail is pinched in the nip which pulls the net along the outer surface of the crop package to effect the dispensing action.
Subsequent to wrapping, the net material is severed by a cutting device, comprising an assembly for thrusting a knife edge transversely through the path of the net. As dispensing continues, net tension increases causing a severing action as the net is pulled against the knife edge. After the net material is severed, the completed round bale is ejected from the baler by lifting the tail gate which opens the chamber rearwardly permitting the bale to be discharged onto the ground behind the baler.
Problems have been encountered when trash, such as stray crop material and other debris from the surface of the crop material package is permitted to engage the net prior to its entry into the dispensing mechanism. These problems become especially acute in balers of the type disclosed in the Underhill patent mentioned above where the net dispensing assembly is in close proximity to rolls that are used to define the chamber in which hay is being formed into a compressed cylindrical package of crop material. In a system of this nature, a buildup of trash could worsen the starting and spreading functions of the net dispenser, leading to reduced performance and in some instances downtime of the baler for time consuming service and costly repair.